Acorn's computers used a variety of Ferranti ULAs, none of which have yet been reverse engineered although high-level models do exist in the form of machine-level emulators.

Acorn BBC Micro Video ULA

Acorn BBC Micro Tube ULA

A 9-tile array. Mark Haysman has donated a part marked Ferranti ULA9C018E-7 8504, which has kindly been depackaged by 3gforensics. We do not yet have photographs of the die.

photo of three generations of packaged parts (Mark Haysman of retroclinic.com)

Acorn Electron ULA

A 12-tile array in a lidded ceramic package (probably labelled 12C021M). Theo Markettos and Sergei Skorobogatov have photographed the die and C.S. has stitched the images and produced a corrected monochrome image of the metallisation layer. No images released yet, no netlist extracted yet.

macrophotograph of the chip in delidded package (Mark Haysman of retroclinic.com)